The home secretary, John Reid, today admitted that the beleaguered immigration directorate was "not fit for purpose" - and warned that people are likely to be sacked over the foreign prisoners fiasco.

Making his first appearance in front of the home affairs select committee since he took over the reins from Charles Clarke in this month's reshuffle, Dr Reid admitted his department was failing to deliver as he refused to rule out the dismissal of immigration officials in light of a "tidal wave" of scandals.

"Our system is not fit for purpose. It is inadequate in terms of its scope, it is inadequate in terms of its information technology, leadership, management systems and processes," he told MPs.

In a written answer released simultaneously with his appearance, Dr Reid revealed that that 85 serious foreign offenders, released from prison without being considered for deportation since 1999, were still on the run.

Dr Reid explained he had had ordered a "fundamental overhaul" of the Home Office Immigration and Nationality Directorate (IND).

Asked if the review meant that no one would lose their job in the IND, Dr Reid said: "Don't count on it." He added: "If there are people culpable, they will have to bear responsibility."

And he told MPs - perhaps mindful of the abrupt termination of Mr Clarke's career as home secretary: "It's not my job to manage this department - it's my job to lead this department."

He said he had this morning issued staff with an eight-point action plan on which to work

Although Dr Reid didn't echo calls for the Home Office to be restructured and broken down into smaller constituent parts, neither did he rule it out, saying his overhaul would take that option "if it warrants it - anything's possible".

But he suggested creating a system of "unique identifiers" for all prisoners, including foreign ones, to ensure they could be tracked through the criminal justice system.

That came after the revelation that four of the initial total of 1, 023 non-deported foreign were in fact "duplicates", reducing the total to 1, 019.

Another idea he floated was recommending the deportation of all foreign prisoners who had served a total aggregate of six months in jail, even it was for a series of lesser offences carrying shorter sentences.

"Nothing less than a full and fundamental overhaul will be sufficient," he promised the Labour MP David Winnick, who had asked if the Home Office bore responsibility to the victims of those crimes committed by non-deported foreign offenders.

He added that he "inherited" responsibility for that situation.

Dr Reid said he had had to deal with a "tidal wave of events" since his appointment just over two weeks ago. He promised to find out "what was responsible - then who" for the mishaps over foreign prisoners and attempts to deport illegal immigrants - the other flashpoint of the grilling.

One Tory member of the committee, Richard Benyon, praised Dr Reid as the "government's best operator", but gave him a six-month deadline to sort the problems at the Home Office.

Dr Reid also showed his characteristic tough side, revealing he had immediately, on becoming home secretary, paid an unannounced visit to the immigration headquarter at Lunar House, joking that this was the only to find out what was going on without the place "smelling of fresh paint".

He promised to publicise who the remaining eight most serious offenders were among the undeported foreign prisoners, but only if that police agreed that was desirable as an operational matter.

He said he shared the "frustrations" of MPs and the public at the failings that had been exposed.

The IND was struggling to cope with a huge rise in international migration with a system that was designed for an earlier era, he said.

"We are in a state of transition from a paper-based system that was not designed for the problems we are facing towards a technologically based system that seems to be on a horizon that never gets any nearer," he said

Dr Reid said he had appointed new immigration minister, Liam Byrne, to take charge of the reform of the IND, because of the qualities he brought to the job, "including management experience".

Tony McNulty, whom he replaces, had been put in charge of police restructuring because of his experience of local authorities and parliamentary affairs, he said.

A written statement published ahead of the select committee hearing this morning revealed revised figures on foreign criminals still at large after escaping deportation.

The total number of cases had now fallen to 1,019 - four fewer than previously thought - but they had now identified 186 serious offenders among them, a rise of seven.

Under the revised figures, the total number of the "most serious" offenders - including murders and rapists - has risen by two to 37.

Dr Reid explained to the select committee was that the current system for identifying foreign prisoners was open to duplication and pledged to introduce "unique identifiers" to help track individuals.

Speaking on The Daily Politics on BBC2, former Conservative leader and home secretary Michael Howard said Dr Reid's comments were an "indictment" of Jack Straw, David Blunkett and Charles Clarke.

"What he's saying this morning, of course, is the most terrible indictment of his three predecessors," said Mr Howard.

"I believe the Home Office was 'fit for purpose', to use his phrase, when I left it in 1997.

"It's a big department, it's a difficult department to run, but it can be run properly.

"What he's confessed to this morning is the result of nine years of neglect by his three Labour predecessors."

The Liberal Democrats called on the Home Office to now be broken up.

Spokesman Nick Clegg said: "The Home Office's combination of institutional overstretch, legislative overload and political interference is conspiring to undermine confidence in our criminal justice system.

"When an organisation is overburdened by an unmanageable number of tasks, things go wrong.

"The debate on the breaking up of the Home Office should now begin in earnest."